1. The Technical Field
This invention is an improvement in display encoding, and deals in particular with the orientation of the objects by the addition of which a diagram is built up. As described herein, the invention relates to chemical structures, but the concept is usable with other applications, such as drafting and composition.
This invention is also to an improvement in display encoding, a technique for interactively entering graphic data into a computer. The improvement is due to a simplification in the orientation, marking, and display of structures on the screen of a CRT computer terminal. As described herein, the invention relates to chemical structures, but the concept is applicable to other types of diagrams, such as logical and electrical diagrams.
A computer may be used not only to process data, but also to facilitate the entry of these data into the computer With text input, for example, the user seemingly enters depictions of characters. In reality, he enters bit patterns, which are the codes that the computer needs. The machine translates these to graphic characters which are displayed. The input of visible graphics instead of arcane code is known as "display encoding". The term, however, is usually not applied to the input of common text, but is reserved for two-dimensional constructions, such as a diagram.
In display encoding, an entity is entered, as is text, by being assembled--on the face of a graphic computer 13 terminal--from smaller constituents. Ease of input, however, is not the sole advantage of display encoding. Throughout the process of assembly, the unfinished entity is visible, so that it can be determined, at a glance, what has been completed, and what remains to be done. The coupling between code and display further ensures that the visible structure accurately reflects the corresponding machine code. If one is correct, so will be the other. Any errors are apparent, and may be corrected prior to the entity's completion. A further, and not insignificant advantage, is that the input structure can be saved for re-display. Coded text is always translatable into visible, legible graphics; but with other applications, reconstruction of the display may require more than the data whose entry the display facilitated. Saving the code generating the display in addition to these data, will make it possible, in subsequent retrieval, to always view the graphic representation of these data, instead of their arcane codes.
A characteristic facilitating the graphic encoding of chemical structures is their flexibility. The appearance of a chemical structure bears as little resemblance to the shape of the molecule as does an electric wiring diagram to the layout of the actual wires This leaves such diagrams insensitive to the distortions, that are unavoidable in display encoding. There is, however, a limit. In FIG. 1, two diagrams are shown, representing the molecule, adamantane. Both diagrams are chemically correct, as they show all the atoms and all their bonds. But this identity will not be revealed by a casual glance, nor even by closer scrutiny. Considerable practice, or pencil and paper, will be required. This difficulty is normally circumvented by an artificial similarity, a "traditional" appearance, that has been adopted for many classes of chemical compounds. Very subtle, and often very personal considerations, determine what distortions are innocuous, and what distortions are objectionable.
Display encoding offers considerable latitude in the manner an entity is assembled. A diagram might wholly be constructed line by line. But it is more efficient to use simple lines only as a last resort, and to construct an entity, when possible, with larger building blocks. Indeed, the efficiency of the typewriter results from its capability of composing text with ready made and well formed characters, which are building blocks preassembled from simple lines.
A computer may be used not only to process data, but also to facilitate the entry of these data into the computer. This is commonly done for the input of graphic data, such as diagrams. The data are entered by seemingly being drawn on the face of the screen of a graphic computer terminal. This is an interactive process, in which the human user repeatedly issues commands, which the machine executes, and in so doing builds the diagram. Able to work with visible graphics instead of arcane code, the user's task is facilitated. Even so, the specification to the computer of the graphic elements (or objects) to be displayed, and of the location of these elements on the face of the screen, together with the orientation of these elements, is not a trivial matter. A variety of methods have been developed to facilitate these tasks. The present invention represents an improvement in two of these, namely orientation of these elements, and screen addressing.
The locations on a display can be specified precisely by means of Cartesian or other coordinates. This is one form of screen addressing. It would however be tedious to have to determine the value of these coordinates, and to have to key them in. Coordinates may, however, be obtained implicitly, thereby avoiding the necessity of keying them in, relieving even the operator from having to know their values. A number of approaches have been developed for obtaining coordinates implicitly. On a typewriter, for example, the type-guide indicates the location where a typed character will be printed. This location can be changed by depressing certain keys, called "function" keys: the space bar, the back space, the carriage-return, and others. On computer terminals, these same keys move a cursor. The cursor's coordinates can be determined by the computer's program as needed, without the human operator having to be importuned, or even being aware of this.
The drawing of a diagram, positioning all lines and characters by means of the above keys, would still be very cumbersome, even-though coordinates are obtained implicitly. The cause is the limited range of motions allowed by the above function keys. These permit the operator to progress only horizontally or vertically, usually in increments not exceeding the width or the height of a character. Graphic terminals, therefore, are often provided with additional function keys, called "cursor" keys. There are several of these, each engraved with an arrow, one pointing up, one down, one left and one right. If one is depressed, the cursor moves continuously, until the key is released, in the direction of the arrow.
More sophisticated yet is the "light pen". The computer senses the motion of the "pen" on the face of the terminal. Internally, it detects and computes the corresponding coordinates. It then displays a trace at the pen's location, the process being executed so rapidly that the input operator is under the impression of drawing free-hand. The user may also use the light pen to point at items (these are called "primitives" or "fragments" or "building blocks") on the screen, thereby selecting one of them, and even to drag it to another location on the screen While this goes on, the computer records, unobtrusively, both the identity and the new coordinates of the repositioned item.
Notwithstanding such sophistication, the light pen is not ideal. For example, keeping the hand raised to the screen for any length of time causes fatigue. Consequently, a number of alternatives to the light pen have developed: "Rand" or "graphic tablet", "joy stick", "mouse", "thumbwheel", "knee controls", "track ball", "touch pad", "touch screen", etc. The variety of these approaches is evidence of the effort to the facilitation of graphic input.
And yet, none of these devices overcomes all the problems inherent in the light pen. Because a character can be typed faster than it can be drawn with a pen, the keyboard cannot be dispensed with. Yet keyboard and light pen (or its equivalents) do not, from the ergonomics point of view, mix well. The alternation between light pen and keyboard taxes the operator. Typing, often done blindly, by "touch", must be interrupted to pick up the pen, requiring the typist to look away from the screen. The keyboard is a digital device, whereas the light pen is an analog device. Touch typists are able to type blindly because typewriter keys are located at fixed positions, evenly spaced, not too far apart yet sufficiently separated to be distinct. With the light pen, in contrast, the target that must be reached on the screen can have many positions It cannot be reached blindly; it requires hand-eye coordination. Unlike the keys, it cannot be reached with a simple motion. Studies in human factor analysis have revealed that subjects waver when pointing at an object. Initially, the target is overshot or undershot, requiring a number of adjustments to "zero in" on it with the required precision.
A difficulty in the construction of graphs from various predefined objects is the fitting of such objects to the parent graph. An object is not allowed to come too near, nor to touch, any part of the graph except through its point of attachment. Therefore, a fit may not always be possible, no matter what the object's orientation.
With complex graphs such as those used in chemistry, parameters can be used which are hereinafter referred to as N4 parameters, which define the orientation of objects to be attached to the parent graph, and are the most troublesome to specify. Commands such as `rotate by 30 degrees` may not provide sufficient flexibility; if expanded to permit specification of the actual number of degrees, the user is generally unable to estimate that number, so that multiple trials may be necessary. Nudging an object with a light pen is slow and requires skill. The same object may be made available in different orientations, but, the larger the number of objects shown, the more extensive will be the menu wanderings required to locate any object. If, to reduce clutter, fewer objects are offered in menus, more of the input will have to be entered by means of simple lines or simple objects, thereby reducing the speed of the input process and rendering it more tedious. All these difficulties increase with the complexity of the graphs.
2. The Prior Art
U.S Pat. No. 4,085,443 to Dubois et al relates to a keyboard operated apparatus for coding and display of chemical structure and other graphical information. A cursor indicates on the display the part of a structural formula which is subject to the next keyboard operation. Alphanumeric characters identify atoms at nodes. The type of bond in any of eight directions from a node toward another node can be registered and displayed. Registering a bond at a particular node, by character and direction, causes the cursor to relocate to the node at the other end of the designated bond. Other movements of the cursor can be effected by the space bar, with the use of directional keyed instructions. FIG. 4 is noteworthy. This patent does suggest entering of graphical information on the keyboard of chemical structures, position by position, by operation of a direction key 5. This would evidently permit attachment of additional input figures, element-by-element, from a predetermined initial cursor position.
U.S Pat. No. 4,205,391 to Ulyano et al teaches inputting to a computer alphabetic as well as topological graphic data, and in particular, the structural formula of chemical compounds. An encoding tablet is provided, as well as an electronic writing means. FIG. 2 is noteworthy. In this device, graphical data is obtained by inputting the graphical data using a pickup sensor 5, symbol generator 17, coordinate pickup 4, and changeable writing member 38. The sensor 24 is used to check that the changeable writing member 38 touches the surface of the writing tablet 1. Other sensors 41,42 indicate axial position of the writing member 38.
U.S. Pat. No. 3,256,422 to Meyer et al relates to an apparatus for automatic encoding and retrieval of topological structures, such as chemical structures. In Meyer, as seen in FIG. 6, a scanning means is employed for coding the structures desired. A coded sheet having a standardized grid is required in order to encode the structures. Optical or light-sensitive scanning means are employed in this patent.
U.S Pat. No. 4,473,890 Araki, teaches a method and device for storing stereochemical information about chemical compounds. Three-dimensional structures of compounds are stored by supplying the coordinates of the atoms in a three-dimensional space represented by X,Y, and Z coordinates.
The entire disclosure of U.S. Pat. No. 4,476,462 to Feldman, issued Oct. 9, 1984 and filed on Nov. 16, 1981, which has been assigned to the U.S. Department of Health and Human Services, as described hereinabove, is expressly incorporated herein by reference in its entirety.